I recently moved my YaBB 2.4 installation to a new server. On the new machine (Ubuntu 10.04 /Apache2) the forum pages each have a 5-6 second delay in loading. I upgraded to 2.5 AE, and it made no difference.

I turned on debugging for Admins, and it shows a large delay between IMSFILE (Load.pl) and LOG (Subs.pl). The full debugging output is included below.

I have searched the web to no avail. Anyone have an idea on what's going wrong here?

The forum server is a 2-core virtual machine running Ubuntu 10.04 under the XenServer hypervisor on a 64-core server that I control. This VM only does two things at this point, the forum and serving up a very small static web site. The static site is very fast, and a php-based large web application running under a separate VM on the same XenServer has no response problems.

Before I moved it, the board was located on a SUSE machine, where it had no such performance issues.

I don't know XenServer, but I do run other VM software. My guess is we are dealing with a resource issue (as it would be with any other case like this). Perl uses a lot of temp resources, plus it has to launch a copy of the executable for every session. How much VRAM have you assigned to that virtual machine? Did you use a off-the-shelf VM or install yourself?? (I'm thinking about swap space). Does the hypervisor have instrumentation?

PHP typically runs inside Apache, so its a bit different than a CGI app.

Is the Ubuntu a server install or a desktop and is it 32 bit or 64?

My 'best guess' is that something has to be swapped out to disk (or virtual disk).

Finally on my thoughts of the moment - have you run top thru term while this is happening???

OS is the 64-bit desktop system, with 2 virtual processors and 2GB RAM. Top shows a steady memory usage of ~500M, no spikes when pages load. No discernible change in processor utilization when pages load, and processor usage is very low.

The only thing I could find on a web search was one person who reported similar problems that went away when HostnameLookups in apache2.conf was set to "on". I tried that, it made no difference. I turned off compression, that made no difference. It would make sense for this to be network-related, since there are no clues in processor or memory usage, but I don't know what else to try.

See if there's a way to watch disk activity in the hypervisor. I think we are dealing with a swap issue.

(just a guess/thought)

You also might try it with a VM built from the 32 bit 'Server CD' and see if that makes a diff. (no desktop to support and no address translation) and possibly tuned differently. I'm a RHEL family guy, LOL and they are all different.

I don't know VM ware, but - it might have to do with the way your virtual network adapter is set up. I was dinking with VirtualBox this AM getting a Centos server image to work. At least in VirtualBox - there's a whole raft of options (connection models) on how to set up your adapter. I really actually read through ( ) their whole chapter on it to grok the subtle differences, and what one could do vs. the other.

In the end I got webmin running and found I had a nice server working. LOL, I have been doing this a long time, but I had forgotten how lonely a headless server (with no CP) is if "YOU" didn't set it up! Doing the work yourself has the enormous value of 'you know where stuff is'...